1. Field of the Invention
The invention relates to a valve arrangement and, more particularly, to a pneumatic control system.
2. The State of the Art
Pneumatic control systems are widely used because of their efficiency, robustness and long life. In the simplest case, a pneumatic switching element (piston, membrane) is activated by an electropneumatic transducer using pressurized air as the pressure medium. The switching element, in turn, manipulates a flow of gas or fluid. All switching elements suffer from leakage to a greater or lesser extent. For that reason, a pilot valve has to be kept in a permanently open state under a corresponding supply of energy, in order to maintain the switching element in its deflected position. In its activated state, an electromagnetic solenoid valve requires a holding power of about 1 W.